1. Field of the Invention
The invention relates generally to a manually operable tool for assembling and/or disassembling a roller chain such as a drive chain for bicycles, motor vehicles, motor driven tools, and the like, and more particularly relates to a compact manually operable tool for removing and/or inserting pins into a roller chain.
2. Description of Related Art
Drive chains are frequently used for the transmission of power, and for timing or synchronizing motions. A principal advantage of chain drives is that they provide efficient positive drive and power capacity. Roller chains are particularly efficient and economical at transmitting power because of the ability of the rollers to rotate when contacting sprocket teeth.
The various components of a roller chain can become damaged or stretched during use, requiring disassembly of the chain, removal or replacement of chain components and reassembly. Because of their design, roller chains cannot be readily repaired with ordinary tools and, consequently, specialized tools for disassembling and reassembling roller chains are a practical necessity.
The disassembly and assembly of drive chains of various types has been an ongoing problem and various tools have been developed for this purpose.
U.S. Pat. No. 1,000,867 to Widmayer et al. shows a device for removing pins from chains. The device has a block-shaped head with two projections which extend through the openings in a chain, which normally receive the teeth of a sprocket wheel. An adjacent projection has a threaded bore for a screw with a pointed end which engages the pin associated with the roller held between the two projections. The screw can be turned to partially force the rivet from the chain, and a punch is then used with a hammer to completely remove the rivet from the chain.
A disadvantage of the device disclosed by the Widmayer et al. patent is that it does not provide a means for positively driving the rivet completely out of the chain, nor does it provide means for inserting a new rivet. Another disadvantage is that the outer surfaces of the outer link plates are unsupported, which might tend to subject them to deformation forces.
U.S. Pat. No. 1,445,326 to Krebs shows a device for separating and repairing chains similar to that of the Widmayer et al. patent. It differs in that an ejector affixed to the screw member is turned to force the pin out of the links, bending the outer link plate outwardly, freeing the pin from the lower links and permitting the roll to be removed. No hammering motion is required, however, the bent outer link plate must be repaired before being reused or, more likely, simply discarded.
The device disclosed by Krebs has the disadvantages of damaging the outer link plate, and, as with the Widmayer et al. device, does not provide means for inserting a new pin.
In U.S. Pat. No. 4,394,810 to Womble, a device is shown which comprises a combination vise and breaker pin for facilitating repair of metal drive chains. The vise serves to pull the links of a chain together so that tension is maintained throughout the chain while links between jaws become loose and readily repairable. This feature is combined with a breaker pin moving within a hollow channel axial of a full thread hexhead bolt. In operation, the breaker pin cooperates with a U-shaped cradle suitable for holding a link. The bolt carrying the breaker pin is then tightened against the chain link bearing pin. A bearing push bolt is then advanced through a threaded channel so that the breaker head is brought into contact with one of the pins in the roller chain. If the pin of the roller chain resists the force being applied to remove the pin, a sharp rap by a hammer should be utilized.
From the disclosed design of the Womble device, it is apparent that the pin removal and vise operate independent of one another. The device, therefore, is not capable of holding a chain together during the removal of a pin. Another disadvantage is that the device is not always capable of positively forcing a pin from a chain, but instead relies on the use of a hammer applied to the breaker pin.
While it is suggested in the Womble patent that the impeller bolt may be used for inserting a new pin and for reconnecting the chain, it is not clear from the disclosure how this is to be accomplished. The Womble device, therefore, does not appear to provide means for positively forcing a pin into a chain.
In U.S. Pat. No. 4,833,875 to Buermann, Jr. et al., a device for assembling a master link with the ends of a roller chain is shown. A movable plate between two stationary end plates has aperture for receiving the ends of the master link pins. The movable plate is moved against the master link pins by rotating a screw threaded member and thereby inserting the two pins.
The Buermann, Jr. device does not disclose means for removing pins from a chain, nor does it disclose means for temporarily holding the chain together.
In U.S. Pat. No. 3,233,402 to Urbaitis, a power saw chain breaker and repair tool is shown. The device includes a rivet extractor which consists of an extending arm in which are adjustably mounted a pair of anvils. To remove a rivet from a link, the anvils are set to support the link and a punch is brought against the face of the rivet. By rotating a stud, the rivet is pushed from the chain. The device also includes separate features for repairing rivets and for forming a new rivet head.
The Urbaitis device has the disadvantage of not providing means for inserting pins or rivets into a chain.
Thus, while various devices are known for inserting and removing rivets or pins from roller chains, a simple, easy to use device, capable of holding a roller chain together during removal and/or insertion of pins, and capable of both inserting and removing pins from the chain without damaging components of the chain, would be highly desirable.